Metal/air fuel cells of the character here concerned with are those electro-chemical devices including one or more pairs of spaced anode and cathode plates, an electrolyte between the plates, and air delivery means to deliver air to the cathode plate or plates. Such cells operate to convert free energy of the chemical reaction generated by and between the chemically reactive parts and/or material going to make up the cells, into electrical energy. In metal/air fuel cells of the character here concerned with, the anodes are generally and preferably established of a desired expendable metal fuel, such as aluminum, and the cathodes are generally and preferably established of a substantially chemically stable electric conductive, catalytic material, such as carbon or silver. The cathodes are preferably micro-porous structures into which air or oxygen can be effectively supplied for introduction into the chemical reaction as an oxidant.
In operation of ordinary metal/air fuel cells, oxygen from the air, or from an oxygen supply at the surfaces of the cathode plates, reacts with the electrons and water of the aqueous electrolyte to form hydroxyl ions. During this reaction, electrons are removed from the cathode plates resulting in a positive charge at the cathodes. The hydroxyl ions travel through the electrolyte from the cathodes to the anodes. When the hydroxyl ions meet the anodes, metal atoms of the anodes react therewith to form water and free electrons, which electrons are suitably collected and conducted from the cells as electric current.
Metal/air fuel cells of the character referred to above can be extremely effective and efficient generators of electric current when precise operating conditions are established and maintained, but are, as a general rule, subject to developing chemical instabilities which cannot be effectively controlled. Further, such cells generally deteriorate or expend themselves at an excessively rapid rate and are subject to a multiplicity of other shortcomings which, to date, have greatly reduced or prohibited their practical application and use.
One major shortcoming of metal/air fuel cells of the character here concerned with resides in the fact that the structures of such cells are most often such that when they are once assembled and put into service to generate electric current, they cannot be effectively turned off or put out of service and must be left to operate until their effective life is spent. That is, until the metallic fuel anodes are completely consumed.
Another common shortcoming in cells of the character here concerned with resides in the fact that when the metallic fuel anodes are consumed or spent, the whole of the cell structures are spent and must be reconstructed before they can be used again. That is, they are such that when the anode plates are consumed or spent, there is no practical way or means whereby those plates can be easily, effectively and quickly replaced without the undertaking of substantial, time-consuming and costly work which constitutes substantial rebuilding of cells.
Yet another common and serious shortcoming found in cells of the character here concerned with resides in the fact that as the anode plates are consumed, they become structurally unstable and tend to break apart and to drop in the cells to collect in such a manner that the material cannot be effectively utilized and in such a manner that the cells are shorted out or otherwise rendered useless.